Some cheeses, more particularly firm cheeses are packaged under a protective coating firstly to prevent drying of the cheeses during their storage and marketing, and secondly to prevent deterioration of the cheeses by microorganisms.
With the exception of coatings in synthetic plastic materials, of vinyl acetate polymer type, waxes are the coating materials the most frequently used.
Waxes of different origins are used for this purpose. Hydrocarbon waxes of petroleum origin are widely used; they are formed of a mixture of paraffins, microcrystalline waxes and optionally mineral oils. This type of coating and its method of application are described in patent application FR 1 453 977.
These coating materials, in particular coating waxes, must have plasticity and malleability, must not be brittle or adhere to the cheese when they are removed for consumption of the cheese.
In addition, these coating materials, in particular coating waxes, must have melt properties. They are liquid at cheese coating temperatures by immersion or spraying (40 to 100° C.). They are waxy and solid at ambient temperature after crystallization of their constituents.
While the hydrocarbon waxes the most frequently used have excellent functional properties and meet every aspect of the above criteria, they nevertheless have a non-negligible environmental impact since, firstly, they are derived from non-renewable resources and secondly, at the time of their incineration or biodegradation (compost), they produce greenhouse gases contributing towards global warming.
Numerous authors have sought to find substitute compounds; mention may be made of coatings in the form of waxes formed of fatty acid mono- and di-glycerides which, compared with hydrocarbon waxes, have defects at ambient temperature. These substitute products:                have lesser mechanical resistance to impacts,        sometimes have a brittle nature with a tendency to flake when removed for consumption of the product, more particularly when a pull-off strip (Tircel®) is used to open the coating; this is all the more the case since a high fraction of crystalline products is used at high melt temperature, such as long chain fatty acids for example,        are sometimes sticky or oily to the touch for products obtained from shorter fatty acids for example whose melt temperature is lower than 40° C.,        are sometimes less resistant to outside attack by microorganisms for example (lipolysis).        
Although some of these coatings, in particular in the form of waxes, exhibit good plastic properties at ambient temperature, a less favourable behaviour of these coatings is nevertheless ascertained at higher or lower temperatures to which they may be subjected throughout the cheese distribution cycle. For example, some products appear too brittle at temperatures of the order of 4° C. whereas others have a very sticky nature with the onset of oiling, adhesion to outer packaging, possible migration of colouring agents or of the glycerol components of the packaging. In addition, the constituents of these coatings have a chemical structure very close to that of cheese triglycerides and have a low molecular weight which may promote their possible migration to and miscibility with the cheese.
To overcome these problems some coating compositions use polymers of fatty acid vinyl esters as water-dispersible coatings. This type of coating and its method of application are described in patent EP 2 044 836. The final product is coated with a film of thickness less than 500 μm, and more particularly less than 100 μm.
However these products do not have the properties required for a coating wax in terms of fusion/crystallization for the coating operation, impact resistance and ease of peel-off removal prior to consumption. Like any coating they are removed by peeling and the depositing of these aqueous dispersions on the surface of cheeses requires a drying operation. In addition, this coating process is included in the very process of cheese ripening and is therefore not strictly speaking intended for the preservation and transport of cheeses.
To improve the peel-off capability and reduce the tacky nature of the coating, some coating compositions use a mixture of a copolymer of vinyl acetate, dibutyl maleate and wax. This type of coating and its method of application are described in international application WO 2007/116020. While the peel-off quality of the coating is distinctly improved, these compositions are also obtained however from aqueous dispersions of copolymers and therefore require a drying phase.
Coating compositions containing block copolymers have also been described.
WO 2009/016 239 describes a composition containing materials consisting of at least two blocks of vinyl monomers of which at least one can be crystallized. These polymers are manufactured in solution using a particular polymerization method called RAFT. This composition of polymers is used in an aqueous dispersion to provide coatings in the form of crystallizable films used as films or surface coatings e.g. metallic or plastic. The coating composition in WO 2009/016 239 is not suitable for providing a coating wax, all the more so a coating wax for food products. In addition the RAFT method uses non-negligible quantities of sulfur compounds known to be highly odorous and hence incompatible for food use. The migration of these compounds in the food product would lead to organoleptic defects.
WO 2009/065 749 describes a polymer compound used as additive in plastic compositions. This polymer is solubilized in a reactive monomer liquid at ambient temperature to be integrated in another polymeric composition. This polymer is not used alone. It is in no way intended to be used as food coating since in this case a final chemical conversion of this polymer would be necessary directly on the product to be coated, which appears to be highly improbable in practice.
Wax of fossil origin therefore remains the solution of most interest at the present time, and hence the most used for coating food products.